1. Field of the Invention
The present invention relates to a zoom lens suitable for a television camera or a video camera, which realizes a wider angle system while satisfactorily reducing lateral chromatic aberration at a wide-angle end.
2. Description of the Related Art
Conventionally, many proposals have been made about a zoom lens, which includes, in order from an object side, a first lens unit which has positive refractive power and does not move for magnification-varying, a second lens unit having negative refractive power for the magnification-varying, a third lens unit having negative refractive power for correcting image plane displacement due to the magnification-varying, and a fourth lens unit which has positive refractive power and does not move for magnification-varying.
In Japanese Patent Application Laid-Open No. 2000-321496, Japanese Patent Application Laid-Open No. H11-030749, Japanese Patent Application Laid-Open No. H10-062686 and Japanese Patent Application Laid-Open No. H09-258102, there is disclosed that a focal length is 5.5 to 4.8 mm at the wide-angle end in numerical embodiments.
Japanese Patent Application Laid-Open No. 2000-321496, Japanese Patent Application Laid-Open No. H11-030749, Japanese Patent Application Laid-Open No. H10-062686 and Japanese Patent Application Laid-Open No. H09-258102 disclose that a focal length is 5.5 to 4.8 mm at the wide-angle end in numerical embodiments. In order to realize a wider angle system, it is necessary to correct secondary spectrum of the lateral chromatic aberration at the wide-angle end. Therefore, an object of the present invention is to provide a zoom lens suitable for a broadcast zoom lens in particular, having a focal length of 4.8 mm or smaller at the wide-angle end, in which secondary spectrum of the lateral chromatic aberration at the wide-angle end is satisfactorily corrected in particular, and to provide an image pickup apparatus including the zoom lens.